Objective
To evaluate the biomechanical effect of a self-made iliac screw plate on the stability of lumbo-iliac fixation construct before and after fatigue loading.
Methods
Twelve fresh lumbo-pelvic specimens from donated adult cadavers with formalin embalm were used in the study. According to whether use the iliac screw plate or not, the specimens were randomly assigned into group A (with iliac screw plate, n=6) and group B (without iliac screw plate, n=6). The bone mineral density (BMD) of L1-4 was measured using dual-energy radiograph absorptiometry. The pedicle screw and iliac screw fixation were given at L3-5, and bilateral facetectomy and diskectomy at L5, S1 level were performed to prepare the model of the intervertebral destabilization. The biomechanical testing was conducted on a material testing machine under 0-600 N compression and
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7-7 N
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m torsion loading modes for the initial compressive stiffness and torsional stiffness evaluation. And then 20 000 cyclic compressive loading of 40-400 N was given to the specimen, the stiffness evaluation was repeated. Then the maximum pull-out strength of screws at every level was measured and compared. Gross observation and radiological observation were performed during experiment.
Results
The BMD values of groups A and B were (1.15 ± 0.13) g/cm2 and (1.12 ± 0.11) g/ cm2 respectively, showing no significant difference between 2 groups (t=0.428, P=0.678). All pedicle screws and iliac screws were inserted in good position; no loosening or breaking of screw was observed during loading. After fatigue loading, the incidence of halo ring around the iliac screws of groups A and B was 16.7% (1/6) and 50.0% (3/6), respectively. The compressive stiffness and torsional stiffness after fatigue loading were significantly lower than those in initial state in groups A and B (P lt; 0.05); there was no significant difference in compressive stiffness and torsional stiffness between groups A and B before fatigue loading (P gt; 0.05). However, group A had higher compressive stiffness than group B (t=2.664, P=0.024) after fatigue loading, and there was no significant difference in torsional stiffness between 2 groups (t=0.410, P=0.690). No significant difference was found in screw pull-out strength of pedicle screws at L3, L4, and L5 levels between groups A and B (P gt; 0.05); however, the pull-out strength of the iliac screws in group A was significantly higher than that in group B (t=3.398, P=0.007). In groups A and B, the pull-out strength of L3 screw was significantly lower than that of L4 and L5 screws (P lt; 0.05). In group A, pull-out strength of the iliac screws was significantly higher than that of L3, L4, and L5 screws (P lt; 0.05); in group B, the pull-out strength of iliac screws was significantly lower than that of L4 and L5 screws (P lt; 0.05).
Conclusion
In the lumbo-iliac reconstruction, the use of iliac screw plate could resist iliac screw loosening, therefore, it has the potential to increase the stability of lumbo-iliac fixation construct.
Objective
To explore the effectiveness of fixation of atlas translaminar screws in the treatment of atlatoaxial instability.
Methods
A retrospective analysis was made on the clinical data of 32 patients with atlatoaxial instability treated with atlantoaxial trans-pedicle screws between March 2007 and August 2009. Of them, 7 patients underwent atlas translaminar screws combined with axis transpedicle screws fixation because of fracture types, anatomic variation, and intraoperative reason, including 5 males and 2 females with an average age of 48.2 years (range, 35-69 years). A total of 9 translaminar screws were inserted. Injury was caused by traffic accident in 4 cases, falling from height in 2 cases, and crushing in 1 case. Two cases had simple odontoid fracture (Anderson type II), and 5 cases had odontoid fracture combined with other injuries (massa lateralis atlantis fracture in 2, atlantoaxial dislocation in 1, and Hangman fracture in 2). The interval between injury and operation was 4-9 days (mean, 6 days). The preoperative Japanese Orthopaedic Association (JOA) score was 8.29 ± 1.60.
Results
The X-ray films showed good position of the screws. Healing of incision by first intention was obtained, and no patient had injuries of the spinal cord injury, nerve root, and vertebral artery. Seven cases were followed up 9-26 months (mean, 14 months). Good bone fusion was observed at 8 months on average (range, 6-11 months). No loosening, displacement, and breakage of internal fixation, re-dislocation and instability of atlantoaxial joint, or penetrating of pedicle screw into the spinal canal and the spinal cord occurred. The JOA score was significantly improved to 15.29 ± 1.38 at 6 months after operation (t=32.078, P=0.000).
Conclusion
Atlas translaminar screws fixation has the advantages of firm fixation, simple operating techniques, and relative safety, so it may be a remedial measure of atlatoaxial instability．
Objective To develop a high-accuracy, better-safety and low-cost cervical pedicle locator system for guiding cervical pedicle screw placement. Methods Cervical pedicle screw locator system was made of stainless steel. Ten cervical specimens from voluntary donation were divided into two groups according to compatibil ity design: control group inwhich 60 screws were planted into C2-7 by free hand; and experimental group in which 60 screws were planted into C2-7 under the guidance of three-dimensional locator system. The condition of screw insertion was observed and the accuracy was evaluated by the integrity of pedicle walls. Results In the control group, 32 screws (53.33%) were placed inside the pedicles and 28 (46.67%) were outside; 9 screws (15.00%) led to nerve root injury, 5 screws (8.33%) caused vertebral artery injury and no spinal cord injury occurred; and the qual ification ratio of screw insertion was 76.67% (excellent 32, fair 14, poor 14). While in the experimental group, 54 screws (90.00%) were placed inside the pedicles and 6 (10.00%) were outside; 1 screw (1.67%) caused vertebral artery injury and no nerve root injury and spinal cord injury occurred; and the qual ification ratio of screw insertion was 98.33% (excellent 54, fair 5, poor 1). There was significant difference between the two groups (P lt; 0.05). Conclusion Cervical pedicle screw locator system has the advantages of easy manipulation, high accuracy of screw placement and low cost. With further study, it can be appl ied to the cl inical.
ObjectiveTo compare the effectiveness of femoral neck system (FNS) and cannulate compression screw (CCS) in the treatment of femoral neck fractures in young and middle-aged patients. MethodsThe clinical data of 82 young and middle-aged patients with femoral neck fracture treated between January 2018 and September 2020 were retrospectively analyzed. They were divided into FNS group (24 cases) and CCS group (58 cases) according to different surgical methods. There was no significant difference between the two groups (P>0.05) in general data such as gender, age, height, body mass, cause of injury, complications, fracture location, and fracture classification (Garden classification and Pauwells classification). The operation time, intraoperative blood loss, complications (nonunion, osteonecrosis of the femoral head, shortening of femoral neck, etc.), visual analogue scale (VAS) score at 2 days after operation, clinical healing time of fracture, and Harris score of hip joint after operation were recorded and compared between the two groups. ResultsThe operation time and VAS score at 2 days after operation in FNS group were significantly lower than those in CCS group (P<0.05); there was no significant difference in intraoperative blood loss between the two groups (t=0.263, P=0.796). The patients in CCS group were followed up 6-18 months, with an average of 13.6 months; and the follow-up time in FNS group was 3-12 months, with an average of 7.3 months. There was no complication of internal fixator loosening in both groups. There were 2 cases of osteonecrosis of the femoral head, 1 case of bone nonunion, and 13 cases of femoral neck shortening in CCS group and only 2 cases of femoral neck shortening in FNS group. The difference in the incidence of complications between the two groups (27.6% vs. 8.3%) was significant (χ2=36.670, P=0.015). In CCS group, 3 cases underwent secondary artificial hip arthroplasty due to bone nonunion and osteonecrosis of the femoral head, and the remaining 55 cases achieved clinical healing; in FNS group, 6 patients excluded in the statistics because the follow-up time was less than 6 months, and the remaining 18 fractures healed clinically; there was significant difference in fracture healing time between the two groups (t=4.481, P=0.000). The difference of Harris score of hip joint between 9 months and 6 months after operation in FNS group was significantly higher than that in CCS group (P<0.05), and the Harris score at 9 months after operation was significantly higher than that at 6 months after operation in both groups (P<0.05). ConclusionFNS can accelerate the healing of femoral neck fractures in young and middle-aged patients, so that patients can start functional exercise as soon as possible, thereby reducing the incidence of related complications.
Objective
To evaluate the clinical and radiographic outcomes of headless compression screws for Lisfranc joint injuries.
Methods
A retrospective analysis was made on clinical data of 34 patients (36 feet) with Lisfranc joint injuries who underwent open reduction and internal fixation with headless compression screws between January 2006 and January 2012. There were 22 males (24 feet) and 12 females (12 feet), aged 21-73 years (mean, 38.9 years). The causes of injury included traffic accident in 16 cases (17 feet), falling from height in 11 cases (12 feet), crushing in 5 cases (5 feet), and sports in 2 cases (2 feet). Of them, there were 19 cases (20 feet) of closed injury and 15 cases (16 feet) of open injury; there were 7 cases (8 feet) of pure dislocations of tarsometatarsal joints and ligamentous Lisfranc injuries (LD), 22 cases (23 feet) of Lisfranc joint fracture dislocations (LFD), 5 cases (5 feet) of combined Chopart-LFD (CLFD). According to Myerson classification, 5 cases (5 feet) were rated as type A, 7 cases (8 feet) as type B1, 14 cases (15 feet) as type B2, 5 cases (5 feet) as type C1, and 3 cases (3 feet) as type C2. Associated fractures included 12 cases (13 feet) of metatarsal shaft fracture, 4 cases (4 feet) of cuboid fracture, 4 cases (4 feet) of navicular bone fracture, 6 cases (7 feet) of coneiform bone fracture/dislocation, 8 cases (10 feet) of ipsilateral lower limb multiple fracture, and 4 cases (4 feet) of contralateral lower limb multiple fracture. The clinical outcomes were evaluated according to American Orthopaedic Foot and Ankle Society (AOFAS) score and visual analogue scale (VAS) score. Postoperative X-ray films were taken to assess the reduction, internal fixation, and the foot arch height.
Results
All patients were followed up 1 year to 5 years and 2 months (mean, 3.5 years). X-ray films showed anatomical reduction in 31 cases (33 feet, 91.7%). At last follow-up, AOFAS score and VAS score averaged 80.6 (range, 60-100) and 2.3 (range, 0-6), respectively; the AOFAS score was significantly higher in patients having anatomical reduction than the patients having no anatomical reduction, in patients with LD and LFD than in patients with CLFD, and in patients without cuneiform bone fracture/dislocation than in patients with cuneiform bone fracture/dislocation (P lt; 0.05). There was no significant difference in the talus-first metatarsal angle, the distance between the lateral edge of the base of the first metatarsal bone and the medial edge of the base of the second metatarsal bone, and the arch height between the injured foot and normal foot (P gt; 0.05). Reduction loss was observed in 1 case (1 foot) because of early weight bearing; post-traumatic arthritis developed in 9 patients (10 feet). The incidence of post-traumatic osteoarthritis was higher in the patients with non-anatomic reduction, coneiform bone fracture/dislocation, comminuted intra-articular fractures of Lisfranc joints, the injury types (P lt; 0.05).
Conclusion
Headless compression screws for fixation of Lisfranc joint injuries can provide satisfactory short- and mid-term clinical and radiographic outcomes. During surgery, the precise anatomic reduction and stable fixation should be paid attention to, especially in patients with CLFD, coneiform bone fracture/dislocation, and comminuted intra-articular fractures of Lisfranc joints so as to control the incidence of the post-traumatic osteoarthritis.
ObjectiveTo evaluate the effectiveness of percutaneous monoplanar screw internal fixation via injured vertebrae for treatment of thoracolumbar fracture.MethodsBetween May 2015 and August 2017, 38 cases of thoracolumbar fractures without neurological symptom were treated with percutaneous monoplanar screw internal fixation via injured vertebrae. There were 22 males and 16 females, aged 25-52 years (mean, 32.5 years). There were 23 cases of AO type A3 and 15 cases of AO type A4. The injured vertebrae located at T11 in 4 cases, T12 in 9 cases, L1 in 11 cases, L2 in 10 cases, L3 in 3 cases, and L4 in 1 case. The mean interval between injury and operation was 4.5 days (range, 3-7 days). The pre- and post-operative degrees of lumbodorsal pain were estimated by the visual analogue scale (VAS) score. The X-ray film, CT three-dimensional reconstruction, and MRI were performed, and the ratio of anterior vertebral body height and sagittal Cobb angle were measured to assess the kyphosis of the fractured area.ResultsAll operations in 38 patients successfully completed without complications such as dural sac, nerve root, or vascular injury. The operation time was (56.2±3.7) minutes and the intraoperative blood loss was (42.3±3.5) mL. All incisions healed by first intention without redness, swelling, or exudation. All patients were followed up 17-33 months, with an average of 21.5 months. The VAS score at each time point after operation significantly improved when compared with that before operation (P<0.05), and significantly improved at 3 months and last follow-up when compared with that at 1 week (P<0.05); there was no significant difference between 3 months and last follow-up (P>0.05). There was no internal fixator loosening, breakage, or delayed kyphosis in all patients. The ratio of anterior vertebral body height and sagittal Cobb angle significantly improved postoperatively (P<0.05), and no significant difference was found between the different time points after operation (P>0.05).ConclusionPercutaneous monoplanar screw internal fixation via injured vertebrae is an easy approach to treat thoracolumbar fracture without neurological symptom, which can effectively restore vertebral body height and correct kyphosis, and avoid long-term segmental kyphosis.
ObjectiveTo design the channels of parallel screws and cross screws for fixation of symphysis pubis diastasis through a small sample anatomic study on pubic symphysis and its neighbor structures so as to provide anatomical basis for minimally invasive fixation of symphysis pubis diastasis.
MethodsEight cadaveric pelvic specimens (6 men and 2 women) were transected along L5 and the proximal 1/3 of bilateral thighs, with intact lumbar spines. The spermatic cord, womb round ligament, and corona mortis were dissected; the distance to the ipsilateral pubic tubercle was measured and subsequently the distance between pubic tubercles, the height of pubic symphysis, the diameter of outer edge of pubic tubercle, the thickness of pubic symphysis and 2 cm outside the pubic symphysis (upper, central, and lower 1/3 thickness of pubic symphysis) were measured to provide anatomical basis for the design of channels of parallel screws and cross screws.
ResultsParallel screw fixation: the entry point of first screw was on the outer edge of pubic tubercle, and its exit point was on the outer edge of contralateral pubic tubercle; a cannulated screw with a diameter of 4.5 mm or 6.5 mm can be suitable for this channel. The entry point of second screw was 20 mm outside the pubic symphysis and 23 mm beneath the pubic symphysis, and its exit point was symmetrical with entry point; a cannulated screw with a diameter of 4.5 mm can be appropriate for the second channel. The direction of two screws was perpendicular to the pubic symphysis. Cross screw fixation: the entry point of cross screws was on one side of the pubic tubercle, and its exit point was 20 mm outside the contralateral pubic symphysis and 23 mm beneath the contralateral pubic symphysis; two cannulated screws with a diameter of 4.5 mm can be chosen for cross screws channels. The direction of two cross screws was intersected with the horizontal line of two pubic tubercles at an angle of 25° respectively; besides, two cross screws formed an anteversion angle and retroversion angle of 5-10° with pubic body plane, respectively.
ConclusionThe channels of parallel screws and cross screws are feasible for fixation of symphysis pubis diastasis by analyzing the anatomical data of the pubic symphysis and its neighbor structures, but further biomechanical research is need to confirm the stability of two fixation methods.
Objective
To compare the effectiveness of cortical bone trajectory screw (CBTS) and conventional pedicle screw for posterior lumbar interbody fusion (PLIF) in the treatment of single segment lumbar degenerative disease.
Methods
Between May 2013 and May 2016, a total of 97 patients with single segment lumbar degenerative disease were treated with PLIF. Fifty-one patients were fixed with CBTS in PLIF (trajectory screw group) and 46 with pedicle screw (pedicle screw group). There was no significant difference in age, gender, body mass index, preoperative diagnosis, lesion segment, and preoperative visual analogue scale (VAS) score, Oswestry dysfunction index (ODI) between 2 groups (P>0.05). The operation time, intraoperative blood loss, postoperative drainage, bed rest time, length of hospital stay, serum creatine kinase (CK) concentration, total amount of diclofenac sodium, perioperative complications, ODI, VAS score, and interbody fusion rate were recorded and compared between 2 groups.
Results
All patients were followed up 12 months. The patients in trajectory screw group had a significantly less operation time, intraoperative blood loss, postoperative drainage, and serum CK concentration when compared with the patients in pedicle screw group (P<0.05). Thirty-five patients (68.6%) in trajectory screw group and 46 patients (100%) in pedicle screw group were given diclofenac sodium within 48 hours after operation, showing significant difference between 2 groups (χ2=89.334, P=0.000). There was no significant difference in the incidence of perioperative complications between trajectory screw group and pedicle screw group (3.9% vs. 8.7%, P=0.418). There was no significant difference in the VAS score, ODI, and interbody fusion rate at 12 months after operation between 2 groups (P>0.05).
Conclusion
For the single segment degenerative lumbar disease, the use of CBTS or conventional pedicle screw for PLIF can obtain satisfactory clinical function and interbody fusion rate. But the former has the advantages of less blood loss, less intraoperative muscle damage, less perioperative pain, shorter length of hospital stay and bed rest time.
ObjectiveTo investigate the effectiveness of spring hook plate for posterior malleolus fracture by comparing with cannulated screw.
MethodsBetween March 2012 and September 2013, 100 cases of posterior malleolus fracture were treated. Fracture was fixed with spring hook plate in 50 cases (research group) or with cannulated screw in 50 cases (control group). There was no significant difference in gender, age, cause of injury, associated injury, and injury to operation time between 2 groups P>0.05). The operation time, intraoperative blood loss, union time of fracture, ankle range of motion (ROM), and complications were recorded and compared. The ankle joint function was evaluated by the ankle hindfoot scale of American Orthopedic Foot and Ankle Society (AOFAS).
ResultsThere was no significant difference in operation time and intraoperative blood loss between 2 groups P>0.05). The patients were followed up 6-12 months (mean, 9.8 months) in the control group and 6-12 months (mean, 9.2 months) in the research group. The X-ray films showed that fracture union was achieved in 2 groups; the union time of the research group[(9.5±1.4) weeks] was significantly shorter than that of the control group[(10.5±1.3) weeks] (t=2.029, P=0.017). The ROM was (25.1±3.2)° for dorsal extension and was (45.3±2.3)° for plantar flexion in the research group at 6 months after operation, which were significantly better than those of the control group[(22.2±2.3)° and (41.2±2.5)°] (t=-3.950, P=0.001; t=-5.212, P=0.000). The ankle hindfoot scale of AOFAS was 85.1±8.6 in the control group at 6 months; the results were excellent in 15 cases, good in 20 cases, and moderate in 15 cases with an excellent and good rate of 70%. The ankle hindfoot scale of AOFAS was 89.4±7.9 in the research group; the results were excellent in 20 cases, good in 22 cases, and moderate in 8 cases with an excellent and good rate of 84%; there was significant difference between 2 groups (t=-2.191, P=0.042; χ2=0.413, P=0.018). Incision infection occurred in 3 cases of the control group and in 2 cases of the research group, which was cured after dressing change; screw loosening and fracture displacement occurred in 3 and 4 cases of the control group, but did not in the research group. The complication rate of the control group and the research group was 20% and 4% respectively, showing significant difference between 2 groups (χ2=6.061, P=0.028).
ConclusionSpring hook plate can shorten the time of union, increase the ROM of the ankle after operation, get good functional restoration, and decrease the rate of complication compared with cannulated screw fixation.
Objective To compare the effectiveness of O-arm navigation and C-arm navigation for guiding percutaneous long sacroiliac screws in treatment of Denis type Ⅱ sacral fractures. Methods A retrospective study was conducted on clinical data of the 46 patients with Denis type Ⅱ sacral fractures between April 2021 and October 2022. Among them, 19 patients underwent O-arm navigation assisted percutaneous long sacroiliac screw fixation (O-arm navigation group), and 27 patients underwent C-arm navigation assisted percutaneous long sacroiliac screw fixation (C-arm navigation group). There was no significant difference in gender, age, causes of injuries, Tile classification of pelvic fractures, combined injury, the interval from injury to operation between the two groups (P>0.05). The intraoperative preparation time, the placement time of each screw, the fluoroscopy time of each screw during placement, screw position accuracy, the quality of fracture reduction, and fracture healing time were recorded and compared, postoperative complications were observed. Pelvic function was evaluated by Majeed score at last follow-up. Results All operations were completed successfully, and all incisions healed by first intention. Compared to the C-arm navigation group, the O-arm navigation group had shorter intraoperative preparation time, placement time of each screw, and fluoroscopy time, with significant differences (P<0.05). There was no significant difference in screw position accuracy and the quality of fracture reduction (P>0.05). There was no nerve or vascular injury during screw placed in the two groups. All patients in both groups were followed up, with the follow-up time of 6-21 months (mean, 12.0 months). Imaging re-examination showed that both groups achieved bony healing, and there was no significant difference in fracture healing time between the two groups (P>0.05). During follow-up, there was no postoperative complications, such as screw loosening and breaking or loss of fracture reduction. At last follow-up, there was no significant difference in pelvic function between the two groups (P>0.05). Conclusion Compared with the C-arm navigation, the O-arm navigation assisted percutaneous long sacroiliac screws for the treatment of Denis typeⅡsacral fractures can significantly shorten the intraoperative preparation time, screw placement time, and fluoroscopy time, improve the accuracy of screw placement, and obtain clearer navigation images.
